Spinal Anatomy Exam 1

What are the 7 basic functions of the spine?

1) Protect spinal cord & nerve roots

2) Passage of spinal nerve to/from spinal cord

3) Support/Stabilize body

4) Developmental origin of ribs

5) Shape/Position body

6) Movement of trunk and limbs (locomotion)

7) Provide horizontal orientation for eye (vision) and vestibular apparatus (balance)

Which spinal cord anchor is an extension of the pia mater preventing lateral movement of the spinal cord?

Denticulate ligaments

What somites give rise to the vertebral column?

Sclerotomes

What germ layer gives rise to somites?

Paraxial mesoderm

(From mesoderm)

What is the process of differentiation from Mesoderm to Perichondral disk?

Mesoderm --> Paraxial mesoderm --> Somites --> Sclerotomes --(migrate around spinal cord)--> Perichondrial blastima --> perichordal fissures --> perichondral disk

What do sclerotomes differentiate into?

Myotomes and dermatomes

What is the intrasclerotomal fissue?

Fissure between sclerotomites of perichondral blastema and give rise to perichordal disc

What is the perichordal disc?

in the location of the intervertebral disk

How many primary ossification centers are there in a typical vertebra?

3

When do the primary ossification centers of a typical vertebrae arise?

BEFORE birth

What are the primary ossification centers of a typical vertebra?

1 in vertebral body (centrum)

2 pairs along vertebral arch (neural arch)

What template does the ossification of the primary and secondary ossification centers use?

Cartilaginous template where centers grow toward one another, decreasing the cartilage

What of the cartilaginous template remains during ossification of a typical vertebra?

Cartilage synchondrosis joint

How many secondary ossification centers are there in a typical vertebra?

5

When do the secondary ossification centers in a typical vertebra arise?

Between birth and late puberty

Where are the 5 secondary ossification centers in a typical vertebra?

2 at epiphyseal plate region (superior and inferior)

2 for tips of transverse processes

1 for tip of spinous process

Where are the cartilage synchondrosis joints in vertebra ossification located?

Between the primary ossification centers (body & arch)

Synchondrosis for each secondary (epiphyseal ring synchondrosis, tip of transverse process synchondrosis, tip of spinous process synchondrosis)

Failure of 2 neural arches to ossify normally posteriorly can result in what pathology?

Spina bifida

What is it called when one ossification center fails to develop and only half of the vertebra body remains?

Hemivertebra (cuneiform vertebra)

Hemivertebra causes what to develop in the spine?

Lateral curvature

What is the primary curvature of the spine?

Kyphotic

What is the secondary curvature of the spine?

Lordotic

Which curvature is the posterior curvature? The anterior curvature?

Posterior = Kyphotic

Anterior = Lordotic

What curvatures are present at birth? Which is a developmental milestone?

Birth = Kyphotic

Development = Lordotic

In what areas of the spine is there a Kyphotic (posterior/primary) curvature?

Thoracics

Sacrococcygeal

In what areas of the spine is there a Lordotic (anterior/secondary) curvature?

Cervical

Lumbar

Which curvature is a concave curvature? Which is a convex?

Concave = Kyphosis

Convex = Lordotic

A Kyphosis curvature is due to differences in __________ height.

Vertebral body height

A Lordotic curvature is due to differences in __________ height

Intervertebral disc height

Kyphosis will increase _________ curve and decrease the ________ curve.

Increase Thoracic/Sacral curve

Decrease Cervical/Lumbar curve

Deviation of a curve toward the posterior aspect

Lordosis will increase _______ curve and decrease the _______ curve

Increase Cervical/Lumbar curve

Decrease Thoracic/Sacral curve

Deviation of a curve toward the anterior aspect

Is having lateral curvature in the spine normal?

Yes!

Slight curvature appears after 6 years of age

Where does a slight normal lateral curvature occur in the spine?

Thoracic and lumbar regions

What was believed to be the cause of the slight lateral curvature in the spine?

handedness

Is the anterior or posterior vertebral body height greater in the thoracics?

Posterior VB height

What are the plate like regions between vertebral bodies C2-Co1?

Intervertebral discs

How many true intervertebral discs are there? Why is this fewer than the regions available?

23

S1-Co1 ossifies w/ age

What are the 6 functions of IVDs?

1) Attach vertebral bodies to eachother

2) Separate vertebral bodies from eachother

3) Help shape spine

4) Acts as powerful ligament

5) Forms anterior border

6) Shock absorber

What is the Annulus fibrosis? What is it made up of?

fibrocartilage ring

- made up of type 1 & 2 collagen

What is the nucelus pulposus? What is it made up of?

Gel like center of IVD

- made up of water, colalgen and proteoglycans

What is the function of the nucleus pulposus?

Allows movement of vertebral bodies

What happens to the intervertebral disc heigh with age?

Decreases due to water and proteoglycan concentrations decreasing

Here are a list of features to generally understand/know for a typical vertebra -->

Superior epiphyseal rim

Pedicle

Lamina

Vertebral foramen

Body (centrum)

Vertebral arch

Superior/inferior vertebral notches

Transverse process

Transverse tubercle

Spinous process

Spinous tubercle

Superior articular process/facet

Inferior articular process/facet

What is the Artery pathway within the vertebral foramina?

Aorta --> Segmental artery --> spinal branch artery --> Medullary (Feeder) artery --> Anterior spinal artery & (2) Posterior spinal artery

What are the two parts of the Medullary (Feeder) artery?

Anterior medullary feeder artery & Posterior medullary feeder artery

When it comes to the spinal branch artery, it can follow another pathway. What other branch other than the medullary feeder artery can it lead to?

Spinal branch artery --> Radicular artery --> rootlets

What is the main plexus for the vein pathway in the vertebral foramina?

Internal vertebral venous plexus

What is the function of the internal vertebral venous plexus?

Provide alternate route for blood

What is a branch of the internal vertebral venous plexus ?

Basivertebral venous vein

Where does the Basivertebral venous vein travel

Through the basivertebral venous foramina

What are the two branches of the internal vertebral venous plexus that lead down the spine?

Anterior spinal vein

Posterior spinal vein

(NOTE ONLY 1 and NOT 2)

What is the anterior boundary of the spinal canal?

Posterior Longitudinal ligament

What is the posterior boundary of the spinal canal?

Ligamentum flavum

What are the 2 functions of the anterior boundary of the spinal canal

1) Prevent hyperflexion

2) Prevent posterior spinal disc herniation

What are the 3 functions of the Posterior boudary of the spinal cord?

1) Preserves upright posture

2) Prevent hyperflexion

3) Straightens spinal column after flexing

What is the embryonic remnant of the nucleus pulposus?

Notochordal tissue

(which becomes nucelus pulposus)

Where is the cartilaginous end plate attached?

Attached to vertebral body and IVD

What is the cartilaginous end plate composed of?

Hyaline cartilage at vertebral body

Fibrocartilage at IVD

What are the 3 functions of the cartilaginous end plates?

1) Prevent vertebral bodies form undergoing pressure & atrophy

2) Contain annulus fibrosus and nucleus pulposus within their anatomical boundaries

3) Allow diffusion of gas/nutrients/waste through pourus structure and allow proper nutrition of IVD

What is the joint classification of the IVD?

Cartilaginous amphiarthrosis symphysis

What is the difference between a synchondroses and a symphysis?

Synchondroses = bones bound by hyaline cartilage (ex: first 7 ribs & sternum --> think LATERAL)

Symphysis = bones bound by fibrocartilage (ex: IVD and pubic symphysis --> think MEDIAL)

The entire outer 1/3 of the annulus fibrosis receives what type of innervation?

Both sensory and vasomotor innervation

What innervates the posterior/posterolateral part of the IVD?

Sinu-vertebral (recurrent) nerve

Why is the posterior part of the IVD sensitive to annular tears?

Heavy distribution of nociceptors (pain receptors)

What is the lateral part of IVD innervated by?

Gray ramus communicans

What is the anterior part of IVD innervated by?

Sympathetic branches from sympathetic trunk/ganglia

IVD have a strong contribution with what types of fibers associated with sympathetic nervous system?

Afferents

Degenerated discs receive _______ innervation by nociceptive and mechanoreceptive endings?

INCREASED

What may be interpreted as back pain?

Disorders affecting IVD

(sensitive to inflammation, pressure, and stimulation)

What is the relationship between spinal nerves and IVD in the cervical region (i.e.: naming)

Spinal nerves exit IVF SUPERIOR to the vertebra of same number

ex: C5 spinal nerve exits between C4-C5 IVF

What is the relationship between spinal nerves and IVD for spinal nerve C8?

Spinal nerve exits IVF between C7-T1

(named like cervical)

What is the relationship between spinal nerves and IVD for the thoracic region down? (i.e.: naming)

Spinal nerves exit IVF INFERIOR to vertebra of same number

(ex: T5 spinal nerve exits between T5-T6 IVF)

What makes up the superior boundary of the intervertebral foramina (IVF)?

Inferior vertebral notch of segment above

What makes up the inferior boundary of the intervertebral foramina (IVF)?

Superior vertebral notch of segment below

What makes up the anterior boundary of the intervertebral foramina (IVF)?

IVD

adjacent part of vertebral bodies

PLL (Posterior longitudinal ligament)

What makes up the posterior boundaries of the intervertebral foramina (IVF)?

Prezygaphophysis

Postzygapophysis

Capsular ligament

Ligamentum flavum

What 6 general things does the IVF contain?

1) nerual tissue

2) connective tissue

3) arteries

4) veins

5) lymphatics

6) ligaments

What percent of the IVF is filled with neural tissue?

8-50%

The spinal branch arteries in the IVF arise from what artery?

Segmental artery

What significant artery is present in the IVF?

Artery of adamkiewicz

The intervertebral veins in the IVF drain into what?

External vertebral venous plexus

Where does the external vertebral venous plexus drain into?

Segmental vein

Where do the lymphatics arise from to form vessels near IVF?

Epidural space

When the lymphatics exit the IVF, they unite with similar vessels in what region?

Perivertebral region

What are the two ligament types in the intervertebral foramina?

1) Transforaminal ligaments

2) Corporotransverse ligaments

Which ligament travels in the IVF from the vertebral body to the INFERIOR articular process of the SAME vertebra?

Superior transforaminal ligament

Which ligament travels in the IVF from the IVD to the INFERIOR articular process of segment ABOVE?

Middle transforaminal ligament

Which ligament travels in the IVF from the vertebral body to the SUPERIOR articular process of the SAME vertebra?

Inferior transforaminal ligament

What ligament travels in the IVF from the vertebral body and IVD to the transverse process of the vertebra BELOW?

Superior corporotrasnverse ligament

What ligament travels in the IVF from the vertebral body and IVD to the transverse process of the vertebra ABOVE?

Inferior Corporotransverse Ligament

What is the clinical importance of the artery of Adamkiewicz?

Often comprised by herniations

What is the function of the artery of Adamkiewicz?

Principle supplier of lumbar enlargement L2-S3

Where does the artery of Adamkiewicz typically enter the spinal canal?

T9/T10 IVF

What is the artery of Adamkiewicz classified as?

Anterior Medullary feeder artery

The artery of Adamkiewicz is the only major arterial supply to what branch along the lower throacic, lumbar, and sacral segments of the spinal cord?

Supplies anterior spinal branch artery

75% of all thoracic IVD herniations occurs below what level?

T8

What 2 back muscles are in layer 1?

Trapezius

Latissimus dorsi

What 3 back muscles are in layer 2?

Rhomboid major

Rhomboid minor

Levator scapulae

What 2 back muscles are in layer 3?

Serratus posterior superior

Serratus posterior inferior

What 2 back muscles are in layer 4?

Splenius capitis

Splenius Cervicis